The embodiments described herein relate generally to electromagnetic machines and more particularly to devices and methods for optimizing magnetic flux return in electromagnetic machines.
In general, electromagnetic machines such as axial flux machines, radial flux machines, conical gap machines, transverse flux machines, and/or the like utilize magnetic flux from one or more magnetic poles (e.g., permanent magnets, electromagnets, induction windings, and/or the like) to convert mechanical energy to electrical energy or vice versa. Such machines typically include windings to carry electric current through coils that interact with the magnetic flux from the magnetic poles via a relative movement therebetween. In some instances, the magnetic poles can be mounted on a movable structure (e.g., on a rotor or otherwise moving part) and the windings can be mounted on a stationary structure (e.g., on a stator or the like) or vice versa. When operated as an electric motor, for example, current can be applied to the windings of a stator, which results in a movement of the magnetic poles (and therefore a rotor to which the magnetic poles are coupled) relative to the windings, thus converting electrical energy into mechanical energy. Conversely, when operated as a generator, an external force can be applied to a rotor of the generator, which results in a movement of the magnetic poles coupled thereto relative to the windings. Thus, a resulting voltage generated by the movement of the rotor relative to the stator can cause current to flow through the windings, thereby converting mechanical energy into electrical energy.
Surface mounted permanent magnet machines are a class of electromagnetic machines in which permanent magnets are mounted on a ferromagnetic structure or backing, commonly referred to as a back iron. Surface mounted permanent magnet machines are often relatively light weight and efficient, yet can be associated with limitations resulting from, inter alia, undesirable constraints regarding the flux return path between adjacent magnetic poles disposed on a backiron. For example, in some instances in which it is desirable to minimize weight of the electromagnetic machine, the size of the back iron (e.g., thickness, width, and/or length) is restricted, which can lead to magnetic flux saturation of at least portions of the back iron. Conversely, when the weight of the electromagnetic machine is not as limited and in an effort to mitigate the effects of saturation, the size of the back iron can be increased, which can increase the cost of the electromagnetic machine due to, for example, increase in material usage. Moreover, in some instances, the scale of the electromagnetic machine can be such that a single, continuous back iron is unrealistic (e.g., in electromagnetic machines used in large scale commercial applications such as, for example, utility grid-level power generation). As a result, the back iron of some such electromagnetic machines can be segmented, which can further lead to undesirable effects associated with magnetic flux density.
Thus, a need exists for improved devices and methods for optimizing magnetic flux return in electromagnetic machines such as, for example, a permanent magnet machine.